Feeding and treating system

ABSTRACT

A feeding apparatus has a vessel with a floor on which is provided a support lining defining with the floor a generally closed space and constituted as a gas-impervious foil formed with a multiplicity of throughgoing holes and a gas-pervious textile sheet bonded to the foil over the holes. A blower serves to inject gas into the space and suck it therefrom and means is provided for withdrawing fluent particulate material from the vessel adjacent the lining. The gas injected under the lining serves partially to fluidize the bed and also to flex the lining so that the bed of particulate material thereon is loosened and can be withdrawn from the vessel.

This is a division, of application Ser. No. 667,822, filed Mar. 17, 1976now U.S. Pat. No. 4,009,393.

BACKGROUND OF THE INVENTION

The present invention relates to a feeding system. More particularly,this invention concerns a feeding apparatus as well as a method offeeding particulate material and a support lining for a feedingapparatus.

It is known to support a fluid particulate material in a vessel on agas-pervious floor. Gas is forced upwardly through this floor so as toloosen the particulate material and even dry it. This upwardly flowinggas increases the fluidity of the particulate material and makes iteasier to withdraw the material from the vessel. Such arrangements areused in feed hoppers and chemical plants, in silos, and in otherarrangements wherein the particulate material is not sufficiently fluentto flow all by itself, particularly where the particulate material issticky or tends to pack or arch.

The floor of such devices is, therefore, usually made of a rigidforaminous sintered metal plate or synthetic-resin body formed withperforations. With such rigid support elements it is possible to achievevery even resistance to throughflow of gas so that the process caneasily be controlled.

The idea of using a flexible support sheet has been suggested. This,however, has been found to be inadequate due to the uncontrollableresistance to throughflow of gas of flexible support sheets, formed, forinstance, of a felted textile or the like. Since the resistance tothroughflow of gas is very low it would be necessary to provide anenormous blower in order adequately to physically displace the sheet onwhich lies a bed of particulate material that must be loosened. Thus thefirst cost and running costs of such an installation are very large.

In order to limit the resistance to gas throughflow in such flexiblesheets it is necessary to increase their thickness considerably. Thishas the concomitant effect of increasing the rigidity of the sheet andmaking it more difficult to deflect it and thereby loosen the materialon it.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide animproved feeding apparatus.

Another object of this invention is the provision of an improved methodof treating and feeding a particulate material.

Yet another object is to provide an improved support element or liningusable in a feeding apparatus as described above.

A further object is to provide an improved method of making such anarticle of manufacture usable as a support lining in a feeding system.

Another object is to provide an improved system which overcomes theabove-given disadvantages.

These objects are attained according to the present invention in anarrangement using a support element comprised as a gas-imperviousflexible foil formed with a multiplicity of throughgoing holes, and agas-pervious flexible textile sheet secured to the foil over the holes.Thus, a fluid can pass in at least one direction through the article,passing through the holes in the gas-impervious foil and thendisseminating through the gas-pervious sheet secured thereover.

With such a system it is possible to make a relatively thin and flexiblesheet which, nonetheless, offers resistance to throughflow of gas ofsuch a high order that the element can readily be deflected by injectingair or another fluid into the space under it. In effect the aggregatecross-sectional area of the holes in the flexible foil has no effect onthe resistance to flow, effected almost solely by the resistance to flowof the sheet secured thereover. Nonetheless, the gas-pervious sheetcovering the hole causes the jets of gas arising from the holes to bespread out in the body of particulate material being loosened.

According to this invention the holes are each at most 4 mm² in flowcross section and are spaced apart by a distance of at most 20 mm. Thesheet secured to the thus-perforated foil is fibrous.

This support element is formed in accordance with the present inventionby gluing the gas-pervious or flexible textile sheet to thegas-impervious foil. It is also possible in accordance with thisinvention to apply a filament to the face of the sheet or the foil, thenjuxtapose the sheet foil, and finally allow the solvent to evaporate sothat the dissolved portion of the sheet or foil integrates with theother element and bonds the two tightly together. It also lies withinthe scope of this invention to heat the sheet or the foil, juxtaposethem, and cool the sheet and foil so that they harden together.

The apparatus in accordance with this invention comprises a vesselhaving a floor, means for withdrawing a fluid particulate material fromthe vessel adjacent the floor, a support lining as described above, andblower means for injecting a gas into the space between the lining andthe floor. Thus the material is loosened by the gas passing through theholes in the foil and disseminating through the sheet.

In accordance with this invention the lining thus formed is annular andhas inner and outer peripheries secured in gas-tight fashion to thevessel so that the space into which gas or liquid is injected issimilarly annular and lies between the peripheries and underneath thelining. In such an arrangement the gas-pervious sheet is turned towardthe material being fed and the foil is turned toward the floor.

It is possible with the system in accordance with this inventionalternately to inject gas into the space under the support lining andwithdraw it so that this lining flexes upwardly and downwardly andserves physically to loosen the material sitting on it. Furthermore, itis possible according to this invention to subdivide the space into twochambers or subspaces and alternately to inflate and deflate thesechambers so as to agitate the material sitting on the support lining.

According to further features of this invention the support lining maybe used to dry the material sitting on it. To this end it may simply beprovided in the bottom of a feed trough or chute that is inclined to thehorizontal so that material charged into the upper end of the feedtrough or chute is loosened and dried as it flows toward the lower endthereof.

According to another feature of this invention the foil is sandwichedbetween two gas-pervious sheets.

Thus with the arrangement in accordance with this invention it ispossible to loosen the particulate material sitting on the lining bothby at least partially fluidizing it with an upwardly passing gas orliquid stream, and to also physically agitate it by displacing thelining on which the bed of particulate material lies. The resistance tothroughflow of gas by the material is almost entirely determined by theresistance of the gas-pervious sheet overlying the gas impervious foil,yet the enormous flexibility and durability of the lining can beascribed to this foil on which the gas-pervious sheet is secured.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross section through an article of manufacture inaccordance with this invention;

FIG. 2 is a top view of the article of FIG. 1;

FIG. 3 is a side schematic view of a feed apparatus in accordance withthe present invention;

FIG. 4 is a vertical section through another feed apparatus according tothe present invention;

FIG. 5 is a vertical section through a particle-treatment arrangement inaccordance with the present invention; and

FIG. 6 is a section similar to FIG. 1 through another article ofmanufacture according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

As shown in FIGS. 1 and 2 a support lining according to the presentinvention comprises a gas-impervious synthetic-resin foil 2 overlain bya gas-pervious textile sheet 1 and formed with a multiplicity ofthroughgoing holes 3. A glue joint 2' secures the two elements 1 and 2together.

As shown by the arrows gas may be applied under pressure to the foilside of the element so that after passing through the foil 2 jets areformed which permeate through the sheet 1. The resistance to throughflowof gas of the element is almost exclusively determined by the resistanceoffered by the textile sheet 1. A tightly woven, felted, or knittedsheet 1 will have a high resistance and a loosely woven, knitted, orfelted sheet 1 will have a low resistance to gas throughflow. The sheet1 may be formed of a polyester or a polyamide as well as a naturalproduct such as wool. It is important that it has a tensile strength of50 kg in a width of 1 cm. Normally a sheet 1 having a thickness between0.2 mm and 1.0 mm is used. The foil may be made of a polyvinyl chloride,polyethylene, polystyrene, rubber, and like flexible materials and has athickness of between 0.1 mm and 0.3 mm. The holes are formed in thisfoil 2 by stamping, burning, or punching. In accordance with the presentinvention the holes 3 are arrayed at a density of 140 holes per dcm². Inthis type of arrangement the gas throughflow is approximately 1 m³ perminute per square meter with a resistance of 100 mm water column. Withsuch a structure the shape or flexion of the liner element does notchange its resistance to gas throughflow.

FIG. 6 shows another arrangement wherein two such sheets 1 are securedto a central foil 2. The foil 2 is made of polyvinyl chloride and isheated on one side at 1' to approximately 160° and united with the onesheet 1 to form a thermal joint. On its other side it is treated with asolvent such as carbon tetrachloride and the polyester sheet 1 isapplied thereto to form a solvent joint 1". The sheets 1 in thisarrangement are of the fabric sold under the brand name Trevira.

It also lies within the scope of this invention to secure the sheet 1and foil 2 together by means other than a glue joint 2', a thermal joint1', or a solvent joint 1". Thus, in particular in installations where asmall surface area of the liner element 1, 2 is needed, it is possiblemerely to press the sheet 1 down on the foil 2. A screen or the like canthus be used to press this sheet 1 down on the foil 2 and ensure a tightcontact therebetween so that in effect the two elements are united.

In accordance with this invention as shown in FIGS. 1 and 6 the holes 3have a cross-sectional area of at most 4 mm². They are spaced apartaccording to the thickness of the foil 2 by a distance of no more than10 mm to 20 mm. The upper surface of the sheet 1, which is of fibrousmaterial in FIG. 1, is roughened.

It is also possible to replace the unitary foil 2 with a foil 2 made outof criss-crossed strips of flexible and gas-impervious synthetic-resinmaterial. In such an arrangement the small spaces formed at thecrossover points will constitute the holes 3. It is also possible simplyto layer on one side of the sheet 1 gas-impervious perforated sheetsthat together form the foil 2.

FIG. 3 shows an arrangement according to the present invention wherein aliner 4 formed as shown in FIGS. 1 and 2 is received in the bottomregion 5 of a cylindrical vessel 6 having a lower region 5a that tapersdownwardly less sharply than the floor 5 over which the element 4 isprovided. The lower region 5a has a flange 50a which rests on a flange50 at the upper end of the floor 5 that in turn rests on a C-sectionsupport ring 9. A seal 13 is provided and the flanges 50 and 50a arebolted together so that the outer periphery of the annular liner 4 issecured in gas-tight fashion between the lower region 5a and the floor5. At the very bottom of the downwardly frusto-conically tapered floor 5there is provided a central axis-defining and downwardly open outletconduit 18. In addition and/or alternatively immediately above thisoutlet conduit 18 is the mouth of another conduit 8 that extendsupwardly and out through a cyclone 15 from the vessel 6. The innerperiphery 11 of the annular lining 4 is clamped between a disc 12 andthe upper end of the outlet pipe 18.

A reversible blower 14 is connected via a conduit 7 to a perforatedmanifold pipe 19 lying in the space between the floor 5 and the liner 4.This blower 14 is operated as shown by the dot-dash line through acontroller 26 also connected to a pressure gauge 17 between the outputside of the cyclone 15 and the suction side of the compressor 16connected thereto. It is therefore possible for the blower 14 to injectair into the space under the lining 4 and cause it to assume theposition shown at 4a in FIG. 3 Periodic pulsating reversing of theblower 14 makes it possible to agitate the bed of particulate materiallaying on top of the liner 4 by moving it between the position shown at4a and a position lying directly on the floor 5.

The controller 26 serves to shut off the blower 14 when a predeterminedsubatmospheric pressure in the cyclone 15 has been exceeded. Thisarrangement therefore ensures that the material would be picked upproperly and separated out in the cyclone 15.

The manifold ring 19 can be replaced by a frusto-conical perforatedsheet 19a forming part of the floor 5, or by other arrangements fordistributing the air feed to the space underneath the liner 4. Inaddition the output holes in the manifold 19 or the perforated sheet 19amay be directed either parallel to the floor 5, or directly at the liner4, or even at an angle inclined to these two directions.

With the arrangement in FIG. 4 the liner 4 has its outer periphery 40and inner periphery 41 secured as shown in FIG. 3. Here, however, thereis provided in the middle of the frusto-conical floor 5 another ring 51secured to an intermediate annular zone of the liner 4 and formingseparate subspaces or chambers 52 and 53. Individual conduits 7a and 7provided with reversible blowers 70 and 71 are connected to the spaces52 and 53 and are automatically operated so as to inject air into theone space while withdrawing it from the other and vice versa. Thus it ispossible to change as shown to the right in FIG. 4 the angle ofinclination of the lower end of the receptacle 6 in order to ensure goodfeeding of the material therein toward the outlet hole 18'.

Finally, FIG. 5 shows a trough 20 inclined to the horizontal andprovided with a screen 27 supporting a sheet 23 as described withreference to FIGS. 1 and 2. A feed device 25 forces air into the spaceunder the sheet 23 so that a bed 21 of particulate material thereonadvances from a feed conduit 22 at the upper end of the trough 20 to anoutlet hole 24 at the lower end thereof. The air fed in by thearrangement 25 not only serves to loosen the bed 21 and make it morefluent, but also serves to dry this bed 21. The gas passing upwardlythrough the bed 21 may be inert or serve to process this bed 21.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofsystems differing from the types described above.

While the invention has been illustrated and described as embodied in afeeding system, it is not intended to be limited to the details shown,since various modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:
 1. A method of treating particulatematerial comprising the steps of:supporting said particulate material ina vessel on a gas-pervious lining; defining between said lining and saidvessel a substantially closed chamber; alternately introducing a gasunder pressure into said chamber and thereby blowing said gas throughsaid lining into said material to loosen same and withdrawing gas fromsaid chamber; and flexing said lining with said gas in one directionduring introduction of said gas under pressure and in the oppositedirection during withdrawal of gas from said chamber to loosen saidmaterial.
 2. The method defined in claim 1, further comprising the stepsof drying said material with said gas after passing same through saidlining and displacing said material with said gas after passing samethrough said lining.
 3. The method defined in claim 1, furthercomprising the steps of aspirating said material from inside said vesselwith suction, and controlling the injection of air into said space inaccordance with the level of this suction.
 4. The method defined inclaim 1, further comprising the steps of:subdividing said chamber intoat least two adjacent compartments; and oppositely and alternatelyflexing said lining at two separate locations corresponding to saidcompartments.